PC87366 Datasheet, PDF (64/240 Pages) National Semiconductor (TI) – 128-Pin LPC SuperI/O with System Hardware Monitoring, MIDI and Game Ports

2.0 Device Architecture and Configuration (Continued)
2.14 KEYBOARD AND MOUSE CONTROLLER (KBC) CONFIGURATION
2.14.1 General Description
The KBC is implemented physically as a single hardware module and houses two separate logical devices: a Mouse con-
troller (Logical Device 5) and a Keyboard controller (Logical Device 6).
The hardware KBC module is integrated to provide the following pin functions: P12, P16, P17, KBRST (P20), GA20 (P21),
KBDAT, KBCLK, MDAT, and MCLK. KBRST and GA20 are implemented as bi-directional, open-drain pins. The Keyboard
and Mouse interfaces are implemented as bi-directional, open-drain pins. Their internal connections are shown in Figure 5.
P10, P11, P13-P15, P22-P27 of the KBC core are not available on dedicated pins; neither are T0 and T1. P10, P11, P22,
P23, P26, P27, T0 and T1 are used to implement the Keyboard and Mouse interface.
Internal pull-ups are implemented only on P12, P16 and P17.
The KBC executes a program fetched from an on-chip 2Kbyte ROM. The code programmed in this ROM is user-customiz-
able. The KBC has two interrupt request signals: one for the Keyboard and one for the Mouse. The interrupt requests are
implemented using ports P24 and P25 of the KBC core. The interrupt requests are controlled exclusively by the KBC firm-
ware, except for the type and number, which are affected by configuration registers (see Section 2.14.2 25).
The interrupt requests are implemented as bi-directional signals. When an I/O port is read, all unused bits return the value
latched in the output registers of the ports.
For KBC firmware that implements interrupt-on-OBF schemes, it is recommended to implement it as follows:
1. Put the data in DBBOUT.
2. Set the appropriate port bit to issue an interrupt request.
KBC ^P12
P16
STATUS
P17
P20
DBBIN
P21
DBBOUT
P26
T0
P27
P10
P23
KBD IRQ
P24
T1
Matrix
Mouse IRQ
P22
P25
P11
Figure 5. Keyboard and Mouse Interfaces
P12
P16
P17
KBRST
GA20
KBCLK
KBDAT
MCLK
MDAT
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